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Showing papers in "European Journal of Applied Physiology in 1977"


Journal ArticleDOI
TL;DR: The findings suggest that in addition to natural recruitment of new motor units the fatigue is characterized by marked reduction in the conduction velocities of action potential along the used muscle fibers.
Abstract: Electromyographic (EMG) activity of m. rectus femoris muscle was registered from young male and female subjects during maintained isometric knee extension at 60% of maximal voluntary contraction. The following EMG parameters were analyzed for the entire fatigue time: integrated EMG (IEMG), averaged motor unit potential (AMUP) and power spectral density function (PSDF). The results indicated a slight but continuous rise of IEMG during the fatigue period. AMUP showed sensitivity to fatigue with increase in amplitude, rise time, and number of spikes counted. PSDF was also easily affected by fatigue so that the total power density curve was shifted towards lower frequencies with a high frequency decay. The mean power frequency decreased linearily as a function of fatigue time. The findings suggest that in addition to natural recruitment of new motor units the fatigue is characterized by marked reduction in the conduction velocities of action potential along the used muscle fibers.

267 citations


Journal ArticleDOI
TL;DR: The metabolic and morphologic adaptation to physical training in skeletal muscle tissue of eleven middle-aged, physically untrained men was studied in this article, where muscle biopsies were taken from the vastus lateralis before, after 8 weeks, and after 6 months of physical training.
Abstract: The metabolic and morphologic adaptation to physical training in skeletal muscle tissue of eleven middle-aged, physically untrained men was studied. Muscle biopsies were taken from the vastus lateralis before, after 8 weeks and after 6 months of physical training for analysis of metabolic and morphologic variables. Glucose tolerance test indicated increased insulin sensitivity after 6 months of physical training. The activities of glycogen phosphorylase, hexokinase and glucose-6-P-dehydrogenase were increased but other enzymes involved in glycogen turnover and glycolysis were unchanged after 6 months of physical training. The activities of citrate synthase and cytochrome-c-oxidase, representing the oxidative capacity were significantly increased already after 8 weeks of physical training. The incorporation rate of palmitate-carbon into CO2 and triglycerides increased, and the incorporation rate of leucine-carbon into CO2 decreased with 6 months of physical training. The fiber diameter of both Type 1- and Type 2-fibers increased, while the mitochondrial volume increased predominantly in Type 2-fibers. Significant correlations were found between metabolic, physiologic and morphologic variables before and after physical training. The results indicate an increased oxidative capacity, mainly located to Type 2-fibers, and an increased utilization of fatty acids in response to this type of physical training.

122 citations


Journal ArticleDOI
Henrik Galbo1, L Hummer, I B Peterson, N J Christensen, N Bie1 
TL;DR: The exercise induced increase in TSH levels possibly explains the increased thyroid hormone secretion rate, which previously has been found in individuals participating in physical training programs.
Abstract: Eight men were studied during graded (47, 77 and 100% of maximal oxygen uptake) and prolonged (76%) exhaustive treadmill running. Plasma catecholamine levels increased progressively with intensity and duration of exercise. Serum concentrations of thyroid-stimulating hormone (TSH) increased with increasing work loads and were 107 (58--243)% (P less than 0.001) above resting values after maximal work. Thyroxine, triiodothyronine and luteinizing hormone in serum never changed significantly. While a small increase in testosterone concentrations (13 [1--24]%) after maximal exercise probably could be explained by changes in plasma volume, a definite increase (31 [14--56]%) occurred after 40 min of prolonged exercise. During continued exercise testosterone concentrations then gradually declined. Testicular stimulation by the increased catecholamine concentrations possible contributed to the rise in testosterone concentrations, but no evidence was found for a direct catecholamine induced increase in the activity of the thyroid gland. The exercise induced increase in TSH levels possibly explians the increased thyroid hormone secretion rate, which previously has been found in individuals participating in physical training programs.

121 citations


Journal ArticleDOI
TL;DR: Well-trained athletes have elevated levels of the serum protease inhibitors alpha-1-antitrypsin, alpha-2-macroglobulin and C1-inhibitor which might limit exercise-induced inflammatory reactions.
Abstract: Eight male subjects (mean age 24.1±2.6 years) performed at intervals of 2 weeks successively a 3 h and two 2 h runs of different running speed. The days following the running there were moderate elevations of C-reactive protein, haptoglobin, alpha-1-acid glycoprotein, coeruloplasmin, transferrin, alpha-1-antitrypsin and plasminogen. There were small or no changes of albumin, alpha-2-macroglobulin and hemopexin. The elevations of the “acute phase reactants” were examined in three male subjects following a 2 h run before and after an endurance training period of 9 weeks. This demonstrated a decreased acute phase response after training as illustrated by the changes of C-reactive protein, haptoglobin and alpha-1-acid glycoprotein in spite of higher posttraining running speeds. Well-trained athletes have elevated levels of the serum protease inhibitors alpha-1-antitrypsin, alpha-2-macroglobulin and C1-inhibitor. These antiproteolytic glycoproteins might limit exercise-induced inflammatory reactions.

102 citations


Journal ArticleDOI
Harri Suominen1, Eino Heikkinen1, H. Liesen1, D. Michel1, W. Hollmann1 
TL;DR: The effects of 8 weeks' endurance training on muscle metabolism at rest and after a submaximal bicycle ergometer exercise were studied in 31 previously sedentary men, aged 56–70.
Abstract: The effects of 8 weeks' endurance training on muscle metabolism at rest and after a submaximal bicycle ergometer exercise were studied in 31 previously sedentary men, aged 56–70. Training consisted of 3–5 one hour exercise bouts per week including walking-jogging, swimming, gymnastics and ball games. The effects of training were similar to those previously reported for younger men. Mean maximal oxygen uptake increased (11%), as did the resting values for muscle glycogen concentration, the enzymes representing aerobic energy metabolism (malate dehydrogenase, succinate dehydrogenase), and also some of the anaerobic enzymes (creatine phosphokinase, lactate dehydrogenase). Lactate production during submaximal work decreased. The enzyme activities were lower following acute exercise both before and after training.

86 citations


Journal ArticleDOI
TL;DR: It was shown that the pedometer does not reflect the differences in energy expenditure levels at different speed very well, and the actometer might be a valid indicator of the daily physical activity in terms of energy expenditure.
Abstract: The purpose of this study was a critical evaluation of pedometer and actometer for estimating daily physical activity.

80 citations


Journal ArticleDOI
TL;DR: Continuous and interval training at 70% and 100% produce identical changes in heart rate response, blood lactic acid concentration and $$\dot V$$ O2 max when the total work load is equated per training session.
Abstract: Fourteen Subjects (6 male, 8 female) participated in a training program upon a bicycle ergometer for 7 weeks. Group CT followed a continuous training regimen 4 days per week at 70% $$\dot V$$ O2 max. Group IT trained by an interval method at 100% $$\dot V$$ O2 max. The duration of each training session was assigned so that each subject would complete 10,000 kpm of work per session during the first week. Each subsequent week, the work load was increased 3000 kpm. Pretraining tests included $$\dot V$$ O2 max, standard 7 min tests at 80% $$\dot V$$ O2 and 90% $$\dot V$$ O2, an endurance test at 90%, and an intense anaerobic work bout at 2400 kpm. Variables assessed were $$\dot V$$ O2, HR, and blood lactic acid concentrations. The mean increase in $$\dot V$$ O2 max was 5.1 ml/kg min (15%) for both groups with a corresponding increase in maximal lactate of 20 mg-%. The response to the post-training tests was nearly identical for both groups: submaximal heart rate at the same absolute work load declined 17 beats/min (CT) and 15 beats/min (IT), submaximal lactate levels declined significantly, endurance ride duration increased 26 min. Continuous and interval training at 70% and 100% $$\dot V$$ O2 max respectively produce identical changes in heart rate response, blood lactic acid concentration and $$\dot V$$ O2 max when the total work load is equated per training session.

75 citations


Journal ArticleDOI
TL;DR: The pedometer results point out that when the percentage of intense activity is high the pedometer tends to underestimate the level of activity and the actometer results indicate that such a motion recorder gives a reliable estimation of activity in children.
Abstract: The validity of the pedometer and actometer for estimating the daily physical activity was evaluated by means of an observation study. The physical activity in a classroom of 11 pupils of a kindergarten was assessed by means of a pedometer, actometer and by observation. Besides this an activity questionnaire was completed by the infant-quide. On basis of the individual observation it is clear that the infant-guide can give valuable information about the activity of the children at school. The results of the pedometer attached to the waist and the actometers attached to the ankle were significantly correlated with the results of the observation method. The wrist actometer showed a smaller but still significant correlation with the other variables. Implications of this findings are discussed in regard toward the physical activity. The pedometer results point out that when the percentage of intense activity is high the pedometer tends to underestimate the level of activity. The actometer results indicate that such a motion recorder gives a reliable estimation of activity in children. The findings are discussed in terms of the practical applications of the actometer in the research of daily physical activity and the physical rehabilitation treatment of certain diseases.

73 citations


Journal ArticleDOI
TL;DR: The importance of pH as the performance-limiting factor must be questioned because the investigation gave no evidence for alterations of intracellular pH.
Abstract: The influence of bicarbonate and Tris-buffer infusions on the performance capacity for maximal, brief exercise (400 m run) was studied using 10 normal males in their twenties. Run time, maximal lactate concentration and heart rate remained unchanged after the buffer infusions. As a result of the induced elevated buffering capacity, the average pH after exercise was about 0.1 unit higher. Corresponding values for base excess and standard bicarbonate were found. The arterial pCO2 was higher after infusion as a result of the active respiratory compensation. Since the reduction in the work-related metabolic acidosis by the buffering substances caused no improvement in performance, the importance of pH as the performance-limiting factor must be questioned because the investigation gave no evidence for alterations of intracellular pH.

69 citations


Journal ArticleDOI
TL;DR: Recommendations have been made for reducing unwanted myotatic reflex activity while using the “suspension method” to obtain estimates of various biomechanical parameters.
Abstract: The passive elastic torque function and the passive viscous torque function of the muscles and connective tissues spanning the elbow joint have been determined in three adult male subjects. The procedure for estimating the passive elastic torque involved measurement of the torque required to passively move the forearm-hand segment, at a constant angular velocity, throughout a complete range of elbow joint motion. The “suspension method” (Hatze, 1975) was used to obtain the estimate of passive viscous torque. Both of these torque functions were shown to be nonlinear functions of the angular displacement of the joint. In order to assess whether myotatic reflex activity was contributing to the damping of the segment, and thereby biasing the value of the torque contributed by passive viscous elements, the surface electromyograms of the biceps brachii and brachioradialis muscles were examined while the suspended body segment was oscillated. In one subject there was firm evidence of involuntary muscle activity in the brachioradialis muscle which tended to distort the oscillogram. This activity was enhanced when the subject maintained a voluntary isometric contraction in a remote muscle group (Jendrassik's manoeuvre). Based upon these observations, recommendations have been made for reducing unwanted myotatic reflex activity while using the “suspension method” to obtain estimates of various biomechanical parameters.

67 citations


Journal ArticleDOI
TL;DR: The ratio of hemoglobin to hematocrit remained unchanged during and after all types of exercise, and the changes in hemoconcentration, plasma volume, and plasma protein concentration reached the highest changes in the first 15 min of exercise.
Abstract: A group of 7 healthy males was studied after maximal exercise and during and after prolonged exercise of two types (approximately at 40 and 67% of their $$\dot V$$ O2 max). Hematocrit, plasma proteins concentration, and hemoglobin were followed. Relative changes of plasma volume and total content of plasma protein were calculated from hematocrit changes. The mean corpuscular hemoglobin concentration was obtained by dividing hemoglobin by hematocrit. After maximal exercise, hemoconcentration with concomitant decrease of plasma volume (−13.0%) was found, with a corresponding increase in protein concentration (+12.9%) and without any protein content changes. Later normalisation at the 30th min of the recovery phase was shown. During prolonged submaximal exercise (67% of $$\dot V$$ O2 max) the changes in hemoconcentration, plasma volume (−7.1%), and plasma protein concentration (+6.9%) reached the highest changes in the first 15 min of exercise, and no decrease in protein content was observed. After them the spontaneous tendency to the normalisation was found. No changes were registered in prolonged mild exercise (40% of $$\dot V$$ O2 max). The ratio of hemoglobin to hematocrit remained unchanged during and after all types of exercise.

Journal ArticleDOI
TL;DR: Peripheral venous blood ammonia levels were significantly correlated with levels of pyruvate and lactate, as these latter substrates exhibited a similar exponential relationship with V O max as was observed with ammonia.
Abstract: Five male and two female subjects each performed a maximal aerobic capacity (\(\dot V{\text{O}}_{{\text{2 max}}}\)) test, and two to four submaximal aerobic exercise bouts (requiring approximately 50 and 80% of the individual's measured \(\dot V{\text{O}}_{{\text{2 max}}}\)) on a motor-driven treadmill. Pre-exercise resting oxygen uptakes (\(\dot V{\text{O}}_{\text{2}}\)) and heart rates were determined and a venous blood sample drawn prior to each work session. These same measurements were repeated at 4, 15, 30, and 45 min of the resting recovery period that followed each exercise experiment. Additionally, at the 30th min of each 45-min submaximal exercise, another peripheral venous blood sample was drawn following determination of \(\dot V{\text{O}}_{\text{2}}\) and heart rate. In all blood samples, the hematocrit and concentrations of ammonia, lactate, pyruvate, glucose, hemoglobin, and total plasma proteins were measured.

Journal ArticleDOI
Enzo Cafarelli1
TL;DR: The rate effect grows with time from the onset of exercise and appears to be related to the central signal to the effort sense, and the interaction of peripheral and central signals suggests a model of the effortsense during exercise.
Abstract: The relationships between some physical and physiological events, and perceived effort were studied at several equivalent work outputs (V) at two pedalling rates (30 and 60 rev·min−1). Subjects judged effort throughout a 4 min exercise bout. After 4 min at any sen it was always more effortful to pedal at 30 rev·min−1 even though there were no differences in VE, VO2 or integrated electromyography per minute (IEMG·min−1) between pedalling rates. Effort was related to VO2 and IEMG·min−1 but it was more effortful to pedal at 30 rev·min−1. Effort was also related to pedal resistance and IEMG of single contractions but was influenced by pedalling rate after 4 min of exercise. At any resistance it was more effortful to pedal at 60 rev·min−1, however, when effort was plotted as a function of resistance after 15 s, there was virtually no effect of pedalling rate. The rate effect grows with time from the onset of exercise and appears to be related to the central signal to the effort sense. The interaction of peripheral and central signals suggests a model of the effort sense during exercise.

Journal ArticleDOI
TL;DR: Post-race changes in hemoglobin, hematocrit, and protein levels indicated that a hemodilution had occurred, possibly as a result of elevated sodium levels.
Abstract: The occurrence of possible prolonged alterations in plasma levels of cortisol, epinephrine, norepinephrine, selected energy metabolites, and water and electrolyte balance was assessed in six highly trained male marathon runners by measuring blood biochemical constituents on the 10th day before and for the three days following the running of a marathon. Post-race changes in hemoglobin, hematocrit, and protein levels indicated that a hemodilution had occurred, possibly as a result of elevated sodium levels. Epinephrine remained elevated until the second day. Cortisol was depressed on the first and third post-race days while variable levels were observed on the second day. No prolonged alterations were noted in norepinephrine, FFA, glycerol, triglycerides, glucose, lactate, and pyruvate.

Journal ArticleDOI
TL;DR: That adaptations to the anaerobic training did occur is evident, but the cellular locus remains to be elucidated further.
Abstract: The effects of a 6 week program of intense, intermittent hill running was investigated in 5 endurance-trained men (34–37 years). Venous lactate responses averaged 10.7 mM×1−1 during training. Biopsies were obtained from the vastus lateralis before and after training for determinations of histochemical classification, phosphagen concentrations (ATP and CP) and activities of total LDH and selected LDH isozymes. Indices of aerobic and anaerobic capacity were also measured. Significant improvements (P<0.01) were noted in training distance and loads employed in leg presses, also part of the training: the treadmill test for anaerobic capacity improved by 16.7% and the terminal blood lactate level increased 14% (P<0.05). No changes occurred in $$\dot V$$ O2 max, body fat per cent or anaerobic power. Muscle ATP concentration increased by 14.8% (P<0.01) whereas the tissue level of CP remained unchanged. Total LDH activity and the LDH isozymes (LDH-1, LDH-5 and LDH-2, 3, 4) were not altered by training. No changes in fibre distribution were observed. That adaptations to the anaerobic training did occur is evident, but the cellular locus remains to be elucidated further.

Journal ArticleDOI
TL;DR: Investigation of the distribution of substrates utilized during prolonged exercise in normal human volunteers with and without ingestion of 100 g exogenous glucose found carbohydrate were progressively replaced by lipids as source of energy.
Abstract: The distribution of substrates utilized during prolonged exercise was investigated in normal human volunteers with and without ingestion of 100 g exogenous glucose. The energy provided by protein oxidation was derived from urinary nitrogen excretion and the total energy provided by carbohydrates and lipids was calculated from respiratory quotient (RQ) determinations. The contribution of exogenous glucose to the energy supply was determined by an original procedure using “naturally labeled 13C-glucose” as metabolic tracer. Protein oxidation provided between 1 and 2% of the total energy requirement; this amount was not affected by glucose ingestion. In the absence of exogenous glucose ingestion, carbohydrate were progressively replaced by lipids as source of energy. Exogenous glucose contributed markedly to total carbohydrate oxidation and decreased the percentage of energy derived from lipids. In addition, ingestion of exogenous glucose resulted in a significant economy of endogenous carbohydrates and permitted to prolong the duration of exercise.

Journal ArticleDOI
TL;DR: It was found that there was no statistically significant difference between the 3 protocols at the 0.05 level, and the correlation coefficient between actual and predicted O2 max in ml/kg×min and that predicted from the åstrand-Ryhming nomogram was 0.723.
Abstract: This study compared the W170 scores of 9 male subjects in kgm/kg X min resultant from the following protocols: 2 X 6 min workloads (3 min rest between each bout), 3 X 4 min workloads (1 1/2 min rest between each bout), and 4 X 3 min workloads (1 min rest between each bout). Each subject experienced 2 preliminary rides in order to overcome the problems of learning and habituation and the order of the 3 experimental treatments was randomly assigned to each subject. An analysis of variance repeated measures design revealed that there was no statistically significant difference between the 3 protocols at the 0.05 level. The scores for the three W170 protocols correlated -0.084, 0.040, and -0.142 with VO2 max in ml/kg X min. The correlation coefficient between actual VO2 max in ml/kg X min and that predicted from the Astrand-Ryhming nomogram was 0.723.

Journal ArticleDOI
TL;DR: In 12–18 year old boys actual steprate on a treadmill was compared to the scores of two types of mechanical pedometers (Russian and German), attached to the waist, and if pedometers register only during running they reflect actual step rate fairly good and give a good estimation of the change in oxygen uptake as speed gathers.
Abstract: In 12–18 year old boys actual steprate on a treadmill was compared to the scores of two types of mechanical pedometers (Russian and German), attached to the waist. Both types show deviations from actual steprate in running at speeds of 8 and 10 km·h−1 of ca. 5% (±9%). In walking or running at 6 km·h−1 and in running at 14 km·h−1 both types give an overestimation of ca. 8.5% (±8%). In walking at a speed of 2 and 4 km·h−1 the scores are not reliable because of the big standard deviation of ca. 34%. Oxygen uptake (ml·kg−1) and heart rate (beats·min−1) increase more in running than in walking, actual steprate (steps·min−1) however increases less in running compared to walking. If pedometers register only during running they reflect actual steprate fairly good and give a good estimation of the change in oxygen uptake as speed gathers.

Journal ArticleDOI
TL;DR: White high school girls and boys aged 14–17 years, selected from 9th, 10th, 11th and 12 grades of a northern, midwest U.S. high school performed running exercise on a motor driven treadmill for determinations of maximal O2 uptake to report data on O2 max.
Abstract: White high school girls (n = 120) and boys (n = 120) aged 14--17 years, selected from 9th, 10th, 11th and 12 grades of a northern, midwest U.S. high school performed running exercise on a motor driven treadmill for determinations of maximal O2 uptake (VO2 max). The mean VO max for all age groups was 40.8 +/- 4.0 and 54.7 +/- 5.6 ml/kg-min-1 for girls and boys respectively. The difference in VO2 max across age groups varied only from 40.2--41.2 ml/kg-min-1 for girls and 54.0-56.3 ml/kg-min-1 for boys. These differences were not significant (P greater than 0.05). The reported VO2 max data are compared with those reported in other studies for bicycle ergometer and treadmill excercise using similar age groups.

Journal ArticleDOI
TL;DR: It has been shown that the quadratic relation between the global integrated EMG of the biceps brachii and the external force resulting from the action of the group of flexors can be extended to each of the muscles of this group (brachialis, brachioradialsis, pronator teres).
Abstract: The study of the relations between the electrical activity of a group of synergistic muscles and the biomechanical parameters characterizing the resultant movement is generally reduced to one of the muscles of this group, this muscle being considered as “equivalent”. This is in particular the case for the biceps brachii in the group of elbow flexor muscles. The validity of this concept in the case of isometric, isotonic contraction can be tested by the simultaneous utilization of surface-electrode and wire-electrode detection techniques.

Journal ArticleDOI
TL;DR: It was discussed that the cardiorespiratory adjustment during the initial stages of work was related to K+ release in working muscles and not to O2 consuming or H+ producing processes, nor to release of Pi or increase of OSM.
Abstract: To evaluate to what metabolic event in contracting muscles heart rate (HR) and $$\dot V$$ E are related, time courses of femoral and cubital venous [K+], osmolality (OSM), pH, PCO2, PO2, [lactate], and [orthophosphate] ([Pi]) at onset of exercise were studied in athletes (TR) and non-athletes (UT) and compared to time courses of HR and $$\dot V$$ E. During ischaemic work with the calf muscles it could be shown that most of these blood constituents were only released from contracting muscles. Thus their time courses reflected the metabolic events in working muscles being not essentially disturbed by non-working parts of the body. Ischaemic work induced, however, substantial increases of HR and $$\dot V$$ E. In the course of non-ischaemic bicycle work HR and $$\dot V$$ E rose more rapidly in TR than in UT but were lower in TR during the steady state. During non-ischaemic work only the increases of femoral venous [K+] closely mimicked the cardiorespiratory transients in TR as well as in UT. None of the other femoral venous substances showed such a rapid change or such typical variations between TR and UT. Cubital venous [K+] and [Pi] approached femoral venous concentrations only in the second minute after start whereas pH, PCO2, and OSM increased mainly in venous outflow from contracting muscles. PO2 decreased in femoral venous blood of TR and UT, but in cubital venous blood it remained depressed only in UT. It was discussed that the cardiorespiratory adjustment during the initial stages of work was related to K+ release in working muscles and not to O2 consuming or H+ producing processes, nor to release of Pi or increase of OSM.

Journal ArticleDOI
TL;DR: The perceived exertion rating (RPE) scale of Borg, showing a closer relationship to work load than to heart rate, seems to reflect perception of physical stress rather than perception of physiological strain.
Abstract: The perceived exertion rating (RPE) scale of Borg was used to investigate the relationship between perceived exertion and pedalling rate. Normal subjects and patients with chronic obstructive lung disease (Cold) were studied in repeated test series. Work load, applied in a random order, varied from 2.5 to 10 mkp/s (patients) and 5 to 20 mkp/s (normals). Pedalling rate varied from 2.5 to 10 mkp/s (patients) and 5 to 20 mkp/s (normals). Pedalling rate varied from 40 to 60, 80, 100 rpm. At constant work load, RPE decreases during increasing pedalling rate. With respect to validity, RPE, showing a closer relationship to work load than to heart rate, seems to reflect perception of physical stress rather than perception of physiological strain. In addition, the results raise the question of standardization of pedalling rate in bicycle ergometry.

Journal ArticleDOI
TL;DR: In this article, the authors discuss the kontinuierliche Registrierung der Herzfrequenz with einem transportablen Cardiocorder berichtet.
Abstract: Es wird uber die kontinuierliche Registrierung der Herzfrequenz mit einem transportablen Cardiocorder berichtet, der die minutliche Erfassung der Herzfrequenz fur Zeiten bis zu 24 Std erlaubt. Das GerAt besteht im Prinzip aus einem zweikanaligen TonbandgerAt, dessen Laufgeschwindigkeit so untersetzt ist, da\ eine normale Tonbandkassette C 60 fur eine Herzfrequenzregistrierung von 2×24 Std Dauer ausreicht. Auf der ersten Spur des Tonbandes werden die R-Zacken des EKG als Biosignale registriert; auf der zweiten Spur wird in minutlichen AbstAnden eine Zeitmarke aufgegeben. Mit Hilfe eines WiedergabegerAtes wird die 24stundige Aufnahme in ca. 15 min abgespielt. Durch einen eingebauten Impulsformer werden die Signale beider Spuren in digitale Rechteckimpulse umgewandelt. Diese in serieller Form vorliegenden Impulse werden durch ein Interface in einen ZAhler mit Hilfe der Zeitmarke in minutlichen AbstAnden gezAhlt; diese Werte stehen in BCD-Code parallel zur Weitergabe fur PeripheriegerAte wie: Schnelldrucker, Rechner, Kompensationsschreiber etc. zur Verfugung. Wird gleichzeitig die korperliche AktivitAt, standardisiert durch Selbstoder Fremdbeobachtung, ermittelt, so lassen sich diese Verhaltensmuster mit den Herzfrequenzwerten zur weiteren statistischen Verarbeitung zusammenbringen.

Journal ArticleDOI
TL;DR: All resisted RT changes were manifested in the muscular component suggesting a peripheral site for neuromuscular fatigue in males assessed for knee-extension task.
Abstract: Fractionated resisted and unresisted RT for a knee-extension task was assessed on 12 male subjects over a 10-day treatment period. The first 4 days were baseline days and were designed to stabilize all RT values as well as strength measures. For the next 6 days the subjects were alternately administered isometric and isotonic exercise designed to fatigue the quadriceps musculature. Although significant strength decrements were manifested for both isometric exercise (57%) and isotonic exercise (35%), no changes were shown in the unresisted fractionated RT components. Conversely all resisted RT changes were manifested in the muscular component suggesting a peripheral site for neuromuscular fatigue.

Journal ArticleDOI
TL;DR: Study of the blood flow distribution within the myocardium showed a slight decrease of the ratio of subendocardial to subepicardial blood flow in the left ventricular free wall in response to exercise, and within the brain there was a relative increase in theBlood flow to the cerebellum.
Abstract: Regional blood flow was measured with the microsphere method in conscious dogs under resting conditions and during moderate exercise on the treadmill.

Journal ArticleDOI
TL;DR: A method of determining quantitatively the rotary flexibility of the elbow joint was developed and its reliability tested and a broader dispersion is clearly recognizeable as the result of ageing, through a drop in the lower limit of deviation.
Abstract: A method of determining quantitatively the rotary flexibility of the elbow joint was developed and its reliability tested. Examinations of the left elbow joint of 100 healthy men between the ages of 18 and 72 were performed, consisting of measurements of passive supination effected by a graduated external torque as well as of active supination and pronation. The purpose of the study was to acquire a norm as basis for the functional evaluation of this joint in playing the violin. The investigation produced the following results: 1. The maximum active range of movement consists of about 160‡, the supinatory portion is generally higher than the pronatory, when related to a zero position with the palm of the hand in the sagittal plane. 2. The range of passive movement is non-linearly dependant on the external torque. 3. The variability of passive flexibility increases with decreasing external torque and is generally higher than the variability of active flexibility. Active pronation varies more than active supination. 4. A close positive correlation between active and passive supination is evident only when a higher torque is applied. The correlation between active supination and active pronation is only 0.33. 5. The statistically establishable reduction of flexibility through ageing is not considered to be characteristic of actual conditions. On the other hand, a broader dispersion is clearly recognizeable as the result of ageing, through a drop in the lower limit of deviation.

Journal ArticleDOI
TL;DR: The need for study of the interactions between age, size and maturity is suggested, in addition to indicators of size and efficiency of the oxygen delivery system, and indices of muscle oxygen utilization efficiency, to permit a more definite partitioning of the variance in submaximal aerobic capacity during growth.
Abstract: Heart diameters, heart volume (HV), PWC 130, $$\dot V$$ O2 at 130 heart rate, and cardiorespiratory reactions during work at 3 kgm·s−1 were obtained in 237 boys ranging in age from 8–18 years. Results indicate that heart size, PWC 130, $$\dot V$$ O130, and exercise HR, $$\dot V$$ O2/HR, $$\dot f$$ and SBP change significantly with age. On the other hand, HV·kg−1 and work $$\dot V$$ O2, $$\dot V$$ E and $$\dot V$$ E/ $$\dot V$$ O2 remain rather stable throughout the growth period. Correlation analysis indicates that about 85% of the observed variation in the size of the heart during growth can be accounted for by body weight, while about 70% of the variation in light submaximal working capacity ( $$\dot V$$ O130) can be explained by HV alone. Holding age, height and body weight constant by partial correlation procedures yields significant relationships between HV and $$\dot V$$ O130 (r = 0.461), and between HV·kg−1 and $$\dot V$$ O130 (r = 0.414). Age, height, weight and size of the heart correlated simultaneously against $$\dot V$$ O130 account for 75% of the variance in the dependent variable. It would seem important to suggest the need for study of the interactions between age, size and maturity, in addition to indicators of size and efficiency of the oxygen delivery system, and indices of muscle oxygen utilization efficiency. Such an approach will permit a more definite partitioning of the variance in submaximal aerobic capacity during growth, and would probably yield a more conservative estimate of the relationship between the size of the heart and submaximal working capacity during growth.

Journal ArticleDOI
TL;DR: The data suggest that the perception of the intensity of absolute work does not differ in groups differing in their level of fitness when studied cross-sectionally, however, significant reductions in perceived exertion occur following physical training.
Abstract: The purpose of this study was to compare the rating of perceived exertion (PRE) and heart rate (HR) in two groups of 60 military personnel who differed in their level of fitness as determined by maximal oxygen uptake (VO2 max). At an initial testing period (T1), Group I represented a sample of personnel not participating in a training program while Group II had engaged in an endurance program (2--4 mile run/day) for 5 months. Six months later (T2), Groups I and II were retested after having participated in the program for 6 and 11 months, respectively. RPE and HR were measured at the end of each min of a 6 min run at an absolute workload of 6 mph, 0% grade on the treadmill. At T1, Group II had a significantly lower HR at each min of work but no difference existed in RPE between groups at any time during the run. At T2, both groups showed a significant decrease in HR and RPE during each min when compared lobgitudinally. The data suggest that the perception of the intensity of absolute work does not differ in groups differing in their level of fitness when studied cross-sectionally. However, significant reductions in perceived exertion occur following physical training.

Journal ArticleDOI
TL;DR: It is concluded that noise, at “safe” levels for human hearing conservation, when not associated with other potentially noxious stimuli does not cause hyperactivity of the pituitary-adrenocortical system.
Abstract: The purpose of this investigation was to assess the modification in the temporal pattern of plasma cortisol levels during exposure to noises of different intensities, frequencies and durations. Plasma cortisol concentrations were measured from 08.00 h to 15.00 h at 10 min intervals in eight subjects on a control day and one or two exposure days. Noise exposures induced no significant increase in plasma cortisol concentration. It is concluded that noise, at “safe” levels for human hearing conservation, when not associated with other potentially noxious stimuli does not cause hyperactivity of the pituitary-adrenocortical system. These results do not tally with those from animal studies where noise is known to activate corticotrophin (ACTH) secretion.

Journal ArticleDOI
TL;DR: The fat breakdown far exceeded the calculated energy deficit, and it is postulated that much of the “surplus” energy was required for synthesis of additional muscle protein.
Abstract: Ten men spent one week in a cold climatic facility performing a simulated arctic military exercise demanding an energy expenditure of 13-16 MJ-day-1. Although the ration pack was adequate, extensive plate wastage led to a negative energy balance of 2.2 MJ-day-1. Fluid intake was also insufficient, with a 3.25% decrease of body weight, and a 9.7% decrease in skin thickness over the cold exposure. Extensive fat mobilization was indicated by a decrease of skinfold thicknesses, an increase of body density, and associated ketonuria and glycosuria. The fat breakdown far exceeded the calculated energy deficit, and it is postulated that much of the "surplus" energy was required for synthesis of additional muscle protein. In the arctic environment, both energy and fluid balances are better maintained because there are few distraction from the simple pleasure of preparing and eating meals.